The present invention relates to a method of handling transmission in a data transmission system, and more particularly, to a method of handling transmission capable of dynamically changing a frequency for data transmission in a data transmission system.
Universal Serial Bus (USB) is a public interface standard for a personal computer to access peripheral devices. Recently, the application of USB has been extended to a large number of consumer electronics and mobile devices. As storage capacity and network speed enters the epoch of Gigabyte, however, the data connection between a computer and peripheral devices requires a higher transmission rate, and USB 2.0 with a highest speed of 480 Mb/S has difficulty in meeting the continuous growing requirement of access rate.
In order to meet the demands for higher data transmission, USB 3.0 made a debut in November, 2008. The USB 3.0 promises 5 Gb/s “Super Speed” data transfers. When operating in “Super Speed”, the USB 3.0 adopts “full duplex” signaling over two differential pairs separating from non-super speed differential pairs. As a result, a USB 3.0 cable contains 2 wires for power and ground, 2 wires for non-super speed data, and 4 wires for super speed data, and a shield. In contrast, a USB 2.0 cable contains only one transmission pair for data. Apart from that, super speed establishes a communication pipe between the host and each device in a host-directed protocol, but USB 2.0 broadcasts packet traffic to all devices. Certainly, the USB 3.0 has many features different than the USB 2.0 and those differences are well known by those skilled in the art, and thus not elaborated on herein.
The USB 3.0 system is compatible with the USB 2.0 system. When the device is identified, the USB 3.0 system decides whether to run in super speed (SS) or high speed (HS). However, when the USB 3.0 system is running in super speed, a phase-locked loop (PLL) clock generator may generate a 5 GHz clock, which allows data to be transmitted in the super speed connection via a frequency of 2.5 GHz. However, this data transmission may generate a noise spectrum near 2.5 GHz, which may interfere with wireless communication such as IEEE 802.11b/g/n or Bluetooth. In such a condition, the wireless data communication is affected by the USB 3.0 data transmission. This may result in a drop in throughput on the wireless link.